The turnover of acetylcholine and choline in discrete areas of the brain and in their subcellular pools will be studied in rats. We propose to use deuterium-labelled choline rather than radioactive choline and to measure both acetylcholine and choline by a pyrolysis gas chromatography method developed by us, in combination with mass fragmentography. Turnover will be studied after making stereotaxic lesions in specific structures in an effort to explore cholinergic pathways. The kinetics of choline transport into different regions of the brain and into synaptosomes will be determined. Labelled choline will be used for most of this work, but in some experiments acetylcholine will also be doubly labelled, in the acetyl as well as the choline moiety. The turnover of other choline-containing compounds - phosphorylcholine, glycerylphosphorylcholine, cytidinediphosphocholine and choline-containing lipids - will also be followed. The acute and chronic effects of morphine on acetylcholine turnover, choline metabolism, and acetylcholine release will be studied. If indicated these effects of morphine will be examined for possible correlation with analgesia, dependency and the abstinence syndrome following withdrawal from morphine; and other narcotic analgesics of varying potencies will be studied in like fashion. The effect of an acetylcholine-releasing lipid, recently isolated by us and found only in neural tissue, on turnover will also be studied. As morphine is an antagonist of this lipid, experiments will be conducted to see if, conversely, the lipid is a morphine antagonist.